Airborne laser swath mapping of the summit of Erebus volcano, Antarctica: Applications to geological mapping of a volcano

The lidar observations reported here have provided the first high precision topographic data on the active craters of Erebus volcano, Antarctica. Digital elevation data are invaluable for geomorphic analysis of volcanoes especially when combined with methods to automatically extract landscape features. The data are indispensable for studying eruptive events and volcano-tectonic processes. Airborne laser scanning or lidar is a rapidly emerging technology to map surface topography with high accuracy and detail, comparable to a 1:1000 scale map. In the austral summer of 2001–2002 airborne laser scanning data were collected in Antarctica over the summit plateau of Erebus volcano. We describe the high-resolution data set from Erebus, products derived from the data and demonstrate how extracted topographic features can be used in the geomorphic analysis of volcanoes. Background is presented on the airborne laser scanning method and on the accuracy estimation of laser points. We describe the computation of a high-resolution DEM with a grid size of 2 m×2 m for the summit area of Erebus volcano. Errors in the DEM are assessed using independent ground-based GPS data and the RMS error is estimated to be ±0.39 m. Visualization methods reveal topographic features that are very useful for geomorphic analysis. Automatic feature extraction and processing is necessary to exploit the high-resolution and accurate elevation data. Methods are described to extract 1D and 2D features and organize them for subsequent analysis. Fitting analytical functions to 3D point clouds or DEMs is particularly effective in extracting topographic features, including planes, higher order surfaces, cones, and conic sections. These methods are used to obtain a quantitative description of the calderas and modern-day crater of Erebus. Especially valuable are the measured surface areas if the lava lakes as these control thermal emissions and gas fluxes from the volcano. Examination of the surface elevations of Ray Lava Lake, Werner Vent and Active Vent indicates that the active vents were more or less in magmastatic equilibrium in 2001 December. Conic segments are fitted to mapped sections of caldera rims to identify the sections buried under younger lava flows or covered by ice and snow. Automatic methods are used to detect and characterize lava channels using geomorphometric maps generated from the DEM.